1. Field of This Invention
This invention relates to a high temperature lubricant for the hot-working of metals, its production and usage.
2. Prior Art
It is known to use mixtures of graphite and oil. When such product is used, a decomposition of the oil takes place, which not only has a disadvantageous effect on the material characteristics of the tool and of the workpieces, but also leads to undesirable emissions into the environment.
It has been proposed to use a precisely defined mixture of alkali sulfate, borax, potassium chloride, sodium triacetate and graphite, possibly together with further additives in the form of an aqueous dispersion, as a high temperature lubricant for the non-cutting conversion of metal (see German Pat. No. 2,046,727). Such is no good for use with metals in hot-working as a liquid melt is necessary.
A high temperature lubricant for the purpose of the hot-working of metals is known which is produced from a melted product of phosphates and borates of the alkali metals and possible of zinc and/or aluminum and an addition of further components. (See German Pat. No. 2,154,232.) Such a lubricant has problems. A solid lubricant, consisting mainly of graphite or tungsten disulfide and sodium fluoride has been proposed, and is used in the form of a paste (see German Pat. No. 2,028,804.) Salt melts, too, do not always completely satisfy the need of the art, especially in case of the production of seamless piper on so-called pilgrim rolling trains or "Konti" trains.
In the case of such known high-temperature working processes, very high temperatures develop as a result of which the viscosity of such melts drops to a point that the bearing capacity of the lubricant film no longer guarantees sufficient lubrication.